Telephone-exchange.



1%. 871,043. 'PATBNTED ov. 12, .1907. -s. A. .N'ORSTROM.- TELEPHONE EXCHANGE; APPLICATION FILED AUG. 28, 1905.

2 SHEETSSEEBT 'IIIIIIIIIIIIIIII 7; 1410/1111 v: M s!" v ""WW II l! minimum" 2Q glmlwl lll v yi'r" III 62 V No. 871,043 PATENTED NOV. 12, 1 907.

's. A. NORSTROM. -TBLEPHONE EXCHANGE.

APPLICATION FILED AUG. 23, 1905.

2 SHEETS-SHEET 2.

a the ordinary holding pawl for a ten-station exchange,

I switching mechanism is not in operation, rests against the-pawl. When the driving pawl is retracted preit in the opposite direction .far enough to cause the and has its projection ready to be struclr and forced outward each time that the driving pawl is retracted. Theresult is that while the special pawl engages the 'zen of the United States of America, and aresident magnet and pawl for driving it. The ratchet wheel UNITED sra rss PATENT OFFICE.

SAMUEL A. NOIKSTROM, OF CHICAGO, ILLINOIS, ASSIGNOR TO CASPER L. REDFIELD, OF

CHICAGO, ILLINOIS.

TE LE PHONE -EXCHANGE Specification of Letters Patent. Application filed August 28 1905- Serial No. 275.340.

No. 871,043. Yatented Nov. 12, 1907.

ratchet wheel after each forward movement, it is not in operative engagement at the beginning of such movement.

On the balance wheel is a pin and on the ratchet To all whom it may concern.

Be. it known that I SAMUEL A. NORSTROM, a citiof Chicago, county of Cook, and State of Illindis, have invented certain new and useful Improvements in Telephone-Exchanges, of which the following is a specification.

My invention relates to telephone exchangesof the party line type and has for its object improvement in the arrangement and operation of such exchanges.

In party line'exchanges of the present kind there is a central oflice from a spring jack in which extend two wires. A series of local stations are connected by branch wires to these main wires. At each local station there is a switching mechanism the most prominent elements of which are a ratchet wheel, and a to engage said pin; If the driving pawl movesunijection on the balance wheel, the flange engages the pin in such a way as to hold the special pawl from engagement with the ratchet wheel,'with the result. that the ratchet wheel must stop when the blank part reaches the ordinary holding pawl. If the driving pawl pauses in its normal position, then the special pawl rests against the ratchet wheel and the flange engages .the pin so as to keep the special pawl in operative engagement. In this case the special pawl is advanced fromits normal position by the action of the magnet and the driving pawl, and when released it returns to its normal position by spring action. I

The ratchet wheel has one tooth .removed, and, when the wheel'isin its normal position, this vacant place in the wheel is about twelve steps away from .holding pawl.

In the accompanying drawings,- Figure 1 is an elevation of the switching mechanism with the front plate removed; Fig. 2 is a section on line 2-2 of Fig. 1; Fig. 3 is a section through the ratchet wheel and its adjustable sector. Fig. 4 is a plan of the clamping bar by means of which the spools oi the magnet are a vertically adjustable; and Fig. 5 is a diagram showing two local stations on a line together with a part of the central cities at the extreme left.

In Fig. 1 all of the pawls and the balance wheel are represented as being actuated by gravity, though they may be actuated by springs if so desired. The operating magnet AA is held between theplates- P and P, as is also the rest of the switching mechanism. The armature A is pivoted at A and is provided with a driving pawl A which engages the teeth of the ratchet wheel B, which wheel is secured to a pivoted spindle B The spools A and A of the magnet are polarized and have their projecting cores supor twenty-two or twenty-three steps for a twentystation exchange.

There is one ordinary holding pawl and one'special holding pawl. The latter comes into operation when desired for the purpose of enabling the driving pawl to advance the wheel far enough for the vacant tooth to pass the ordinary'holding pawl. The special holding pawl'has a pin which engages a slot in a balance wheel, This wheel has a projection which, when the the driving pawl or the lever which operates it. In this position the slot for the pin in the special pawl enables that pawl to engage the teeth ofthe ratchet wheel. When the driving pawl moves to advance the ratchet wheel, the balance wheel follows it for a short distance, the slot in the wheel moving on the pin in limit the armature movement. The ratchet wheel B has one tooth removed as shown at B In a tenstation exchange the space or blank part B would be paratory to again advancing the ratchet wheel, it strikes the projection on thegbalance, wheel and drives ratchet wheel is in its normal position.

Fig. 1 shows the driving pawl A as located between the blank space B and the holding pawl B. To enable the drivingpawl to operate past this blank .SPZL Ce it is provided with two teeth. It the holding pawl is located between the blank space and thedriving pawl, then the driving pawl needs but one tooth. On the face of the ratchet wheel B is a sector 0 having a flange 0 and two spring prongs O which embrace the spindle'B The endsof these prongs are bent slot engagingthe pin to lift the special .pawl clear of the ratchet wheel, which is the condition at thenext forward movement of thedrivingpawl. The weight of the balance wheel and the force applied for moving its-projection in the direction of the..driving pawl are so related to the speed with which that pawl, is normally operated that the said balance wheel is inward l wheel is an adjustable sector having a flange adapted forrnly and continues to deliver blows upon the proacts as a holding pawl and the driving pawl can move the blank part of the ratchet wheel past the'regular' twelve steps away from the holding pawl B when the ill-midare adapted to enter a groove B! in the wheel B. a A mil; clamps the. sector- 0 in position, or it maybe held in p'ositionb'y the spring action' of the prongs between the wheel B and a'fixed c'ollar where she-unto? is located. As thus made thesector ma readily rem'ovedand is adjustable to any desired 1ms'iti on;with respect to the blank space in the wheel B.

Pivoted at -C- are a special. pawl C and a balance wheel -The. pawl C falls by gravity into the teeth of the wheel B, and the balance wheel D has part of the uPl Pfirftidn cu away, so a to make it lighter, than t the lower-portion. -The remaining weight of the bid-- I in the wheel- D. When the'parts are in their normal ance wheel D is so distributed as to tend to-fall in the same direction that the special pawl lalls. This movem ent is stopped by a projection or lug D- striking and-resting against the back of the driving pawl A when said pawl is in its normalposition. -When the driving pawl A is moved from its normal position tov advance the ratchet wheel'B. the upper part of the balance wheel; follows thismovement until the'projection D'- rests against a stop pin B". When the driv-. ingQp a'wl' A returns to its normal position, it strikes the project-ion D and drives the-upper part of the bal- .pdsitionthe pin C occupies about the position in the slot D. that is shown in. Fig. when the lug or projec't ion D is struck by the pawl A in returning from a ratchet wheel driving movement it forces the upper part of the balance wheel D to the right and this carlies the pawl C' with it so as to clear the-teeth of the ratchet wheel B. The weight of the balance wheel D sand of the pawl Care such that-their return movement towardthe ratchet wheel B is sluggish. This is to prevent the spe .ial pawl C from engaging the teeth of the ratchet wheel B until'the driving'pawl A has started to return aitera driving operation; This movement, however. is. not so sluggish as to prevent the lug D from arriving at a position to be struckas before described the time this pawl begins to advance the ratchet wheel B, then the flange 0 pass outside of the pin .On the balance wheel ,D is a pin D so located that when the balance wheel'is in its normal position the distance of this pin from the center of the ratchet wheel B is slightly greater than the distance of the flange O-', from the'same center. ',The sector Obeing adjustable about this center; the forward edge'of this flange may be normally at any desired distance from this pin.

Thisdistance varies for different stations on the party line. For the first station this distance is a trifle more "than the space between one tooth and'the next: for

the second station it is a trifle, more than the space for two teeth; and so on. Ii. when the forward edge of the flange O} is close to the pin D the ratchet wheel driv- 'ing movement begins-from a position of rest with the special pawl C in engagement with the teeth of the ratchet wheel. then the flange O will pass insideof the pin D and the return blow of the pawl A on the projection D cannot drive the balance wheel D far enough to lift the pawl. C from the ratchet wheel B. In this position the driving pawl A can drive the blank space B past the pawl B. If. however. the-- balance whe el D'is. driven outward by the pawl A at SD with the result that the pawl C will beheld out of B beyond the holding pawl B Back oft-he'ratchet wheel B are a series of contact springs two of which. 3 andil3, are provided with cords E which extend. to'and wrap around the spindle B.

sion from thesesprings is put upon the spindle'B At the first forward step of the ratchet wheel B the springs 3 and- 13 are drawn inward'and have their electrical connections broken with-the springs immediately outside of them. If the ratchet wheel B does not advance far enough for the -blank space B to pass the holding pawl B then the springs 3 and lSQardnotmmed far enough to connect to the adjacent inner springs. When the ratchet wheel is released the springs 3 and 13 act to return it to its normal position. i

when a'current flows through it in one direc tion it oper- Whcn a current flows in the oppositcdirectionit moves l a Ine ther case, after the current ceases the driving pawl returns to its mid-position in the ordinary manner.

wheel, a small projection on the rear of the pawl A strikes the pin D and raisestha't pawl clear of the ratchet'wheel. The lever A also pushes on the lug pawl is also released by the same movement. hen the driving pawl A is at thev extreme of its driving movement. it comes into electrical connection with a stop screw- F which is provided with a conductor exparty line. "he pawl A through the leverA is provided with a conductor to the other branch so that the branches.

set including receiver R, hook H, generator G, a highwound biased ringer Q which issilnply an ordinary .polarized ringer with its armature held to onc'side by a spring so that it maybe operated by-a pulsating current, an emergency key Land certain contact springs and connections as shown and as will appear from the description of the operation.

At the central office are a jack J, a plug P, a drop S, a. battery X, keys M and N for sending impulses in oppoconnections-as shown. There is, of course, an ordinary telephone set provided with connections to the plug invention they are not shown. The keys M and N cessity of illustratingand explaining, in the present application, a. fully organized calling device for'sending the kind of impulse needed.

The two stations illustrate'din Fig. 5 are marked N0. '1 and No. 2, and, for the purposes of description. it will be assumed that the subscriber at station No. 1 wishes '15 talk to the subscriber at station No. 2. Upon turnen'gagementwith the ratchet wheel In this condition, the pawl A cannotadvance the. blank space (See Fig. These cords are provided with suitable screws and adjusting nuts E by means of which a ten- The propelling rnagnct'A, A is polarized so thatthe pawl A in the other direction and causes a release.

When the pawl A moves from its normal position in a direction opposite to that in which it drives the ratchet C to move and raise the special pawl (T. By a suitable connection A ironi the lever A to the pawl B that final part of an advance movement bridges these two At eachv local station there is an ordinary telephone.

are shown for operating the exchange to avoid the ne ates the pawl A' to advance the ratchet wheel B. I

tending through a condenser W. to one branch of the site directions overthe-party line, and contacts "and l 2 0 but as they are unnecessary to an understanding of the 16-17 G. This operates the drop S and calls the operator who inserts plug P in the jack 1. Upon being informed in the ordinary manner that station No. 1 wants station No. 2,,the operator presses key N a series of times. Upon the first contact a current flows: Xl819 .N' 2021-1112 of each station-'22--- A, A 56 -723-242526X. This advances all ratchet wheels one step each-and brings the flanges I O on the sec ors O one' step nearer the pins D. Upon ratchet wheel.

makes a similar pause after the second con tact so that the breakingth'is circ rit the pawl A? returns to normal position and drives the upper part of the balance wheel D outward so afls-t0 lift the special pawl C from the ratchet wheel, and also so as to bring the pin D inside of'the line of movement of the flange 0?. If the second contact at key N immediately follows the first, then the second forward step of the ratchet wheel B at station o. 1 will cause the flange O to pass outside of the pin D and, as a consequence, the special pawl C will be'held away from the ratchet wheel during the remainder of the forward movement. But as station No. 1 is one of the two stations wanted, the operator pauses after making and breaking the first contact with key N for a timesufiic'ient topermit the lug'D- to settle back against jthe pawl A Then when .she makes the second, contact to again advance the ratchet wheels. the flange O of station No. 1 passes inside of the pin D and the pawl A is thereafter prevented from driving the pawl C out of'operative engagement with the As station '2 is also wanted she flange O of that station will come inside of the pin, but

as -other stations arenot wanted shemakes no. similar pause' after the other contacts. This cahsesthe pins D of those'stations to come inside of the flanges O.

- lithe exchange is a ten station one, then the blank spaces B come to the holding pawls B at the twelfth contact made by the operator and all of the ratchet wheels come to a stop at this point except the selected two which have theirspecial pawls C in operative engagement with the ratchet wheels B. When the wheels have been advanced far enough for the blank spaces B to reach the holding pawl B, the springs 3 and 13 have been moved inward far enough to connect to the adjacent springs 32 and 38. -At the first step which carries the blank part B beyond the holding pawl B these springslare moved still further inward and close 38 to 37 and 28 to 29. When the ratchet wheels of selected stations reach this position, the extra resistance thrown upon the cords E by the additional I springs serve to prevent further advance, or a permanent stop may be put behind the springs as shown at E in Fig.s5. When these springs are closed as de- 'scribed branches are provided for the'impulses being sent fromthe central ofiice as follows:'12-27'-28 2930 Q3152H1-3234etc. This calls the subscriber. With both receivers removedand beginning at station 'No. 1, the talking circuit is R3334- scriber may connect his generator to, and call the central oflice over, a busy line. From thegenerator to the line on one side the connection is:G132-3- i- 56. on the other side it is:-G-17163540 414238131211. This is made possible because at the stations not selected the blank part B is as far as the holding pawl B and in this position connections are closed to. springs 32 and 38, although not to springs 29 and 37.

Referring to the original current for operating it will be seen that it goes through the line 12 and branches to 22 adjacent to thecondenser W. This condenser stops the battery current used for operating the magnet but becomes charged by reason of that current. Also ex- I tending from the line 12, buton the opposite side of the "condenser from the branch 22, is the branch 45 leading to the stop screw F.

As before described, when the magnet is actuated to advance the ratchet wheel, the driving pawl A makes electrical connection with the screw Rat its extreme movement thus bridging lines 12 and 5 by way of 45- are of short lengths, the efficiency of the discharge is not depcndentupon the length of the party line as would be the case with a condenser at the central oflice. The consequence is that the efiiciency is the same at all stations.

What I claim is:-

1 The combination with a central oifice. a party line, and a series of local stations connected to the party line,

of switching mechanisms at the stations adapted to be advanced by impulses sent from the central ofiice, means by end of a predetermined number of steps, and means controlled from the central oilice for causing the switching mechanisms of selected stations to move beyond their normal stopping points.

2. The combination with a series of switching mechanlsms located at a series of stations, and means for simultaneously advancing them, of means forming part of each switching mechanism by which all are automatically stopped at a predetermined point, and means controlled from a distance for causing selected switching mechanisms to move beyond their stopping points. 3. The combination with a switching mechanism adapted to be normally stopped at a predetermined point in its advance-movement, and means for causing its advance beyond its normal stopping point, of a telephonic connection arranged to be closed by such extra movement.

4. The combination with a switching mechanism adapted to be normally stopped at a predetermined point in its advance movement, and means for causing it-tondvance beyond its normal stopping point, of an emergency signaling connection closed by the switching mechanism at its normal stopping point, and a telephonic connection closed by a movement beyond the normal stopping point.

5. In a switching mechanism, the combination with a ratchet wheel having one tooth removed, a driving pawl, and a holding pawl, of a special pawl normally out of engagement with said wheel while being advanced, and means'for' causing said special pawl to engage said wheel so that the driving pawl can advance the ratchet wheel with its toothless part beyond the holding pawl.

6. In aaswitehing mechanism, the combination with -21 FA A-46. This contact between A and F ex-- which all switching mechanisms automatically stop at the the connections through which the discharge occurs ratchet wheel and a drivingpawl therefor, of a special pawl, and means controlled by the movement of the ratchet wheel for holding said special pawl either'ln or out ,of en-' gagement-with said wheel.

- 7. The combination with a ratchet wheel, and a driving pawl'theretor, of a special pawl, a locking device tor holding said special pawl either in-or' out'of. engagement with I for advancing it, of contact springs closed by the forward said wheel, and means for controlling the operation oithe locking device by the movement of the driving pawl.

8.: The combination with a ratchet wheel having on tooth removed a driving pawl, and a holding pawl, '61? a special pawl for enabling the, driving pawl to move the toothless part'of the ratchet wheel-past the'holding pawl, and means controlled by the movement of the driving pawl for'controlling the engagement or non-engagement of said special pawl.

.9. .The combination with a ratchet" wheel having one toot h removed, a driving pawl, and a holding pawl, of a special pawl-for enabling thedrlving pawl to move the toothless part of the-ratchet'wheel past the holding pawl a locking device for holding the special pawl in or outof engagement with the wheel, and means for operating said lockingdevice" by the movement of said driving pawl.

- 10. The combinatlon with a ratchet wheel havingone tooth removed, a driving pawl, and a holding pawl ot a special pawl for enabling the driving pawl to move thetoothless part of the ratchet wheel' past the holding pawl, means-for controlling the engagement or non-engagement of said special pawl by the movement of the driving pa'wl, and a locking device carriedby the ratchet wheela'nd arranged -'to hold'the specialpawi in the ,position'determined by thedrivlngpawl. 11. In the swltchinginechani'sm of a telephone exchange,

the combination with-a movable ratchetwheel, ofa pawllocking device-carried by said wheel and a pawl arranged",

' to beheld 'inither of twojpositions by said locking device.

12. ln the switchingniechanlsm ofa telephone exchange. 1 the combination with a movable ratchet wheel of a pawllock'ingdevice carried by' said wheel and adjustable with respect tber'etoJ. 1

13. The combination/with a movable ratchet wheel, of I an adjustable .pawl lockhig device, and means for securing said device at' l y desired position on said wheelfi 14. The combination with a switching mechanism, "a,

-in telephonic connection with-a partyv line, a switching magnet for operating it, :and'an electric circuit by which impulses may besent through said magnet-tot a condenser located in a' normally open bridge between the branches of said circuit, and means hy which said'bridge is temporarily closed onceddringedchforward movement of .saidswitch ing mechanism. I

. '15. The combinationfwith-a'switching-mechanism, and a propelling' magnettherefor, of a circuit for operating said magnet, and means associated with'said circuit ,for

. neutralizing the residual magnetism of said magnet at the I normal 'posit ioni f 'termination of each operation thereof.

'atcach, station normally ,connected in br yond a predetermined-point :17. The combihation with a ratchetfwheel, and means for advancing it, of two" contact springs provided with connections to said wheel for'returning it to normal posi- ,tion-when released, and telephonic connections closed by the compression of said springsupon the advance of said wheel. r

1-8.' The combination with a ratchet wheel, and means movement 01'. saidwheel,'automatic'meansfor normally stopping said wheel before said .springs are closed, and

at a predetermined point in their advance, of means for moving selected" wheels beyond their normal stoppin points, and means whereby the magnets used for advancin I the wheels servealso forselecting, desired wheels for fur ther advance.

20. "The combination with a party line consisting of two conductors leading to aseries of local -statlons, of a switching mechanism at each station permanently conn'ectedrin-hridge of said conductors. -a telephone receiver of said conductors, circuitmaking and breaking devices in said last named bridges and located on each side of said receivers, means by-which upon operating said switching mechanism by impulses sent over ,said'line the ,last named bridges will be broken on both sides 'of'said receiversjand means by which upon advancing the switching mechanisins lie-- the bridges for said receivers will be again closed.-

. v I 21. The combination with a party line consisting of two 22; The combination with'aseries of stations normally,-

mechanism at each station and means controlled from a 1 central 'oifice-for operating said switching mechanisms to, simultaneously break all telephonic connections and subsequently to reestablish the telephonic connections of se: lected stations. of emergency devices at each station so arranged that an unselected station may signal the central gency devices are inoperative until the selective operation is compleled.

Signedat Chicago, 111., this 18th day of August 1905.

SAMUEL A. XORSTROM.

Witnesses: v

A. L. BUCHANAN, v C. L. REDEIELD.

conduct ors leading to a series. or local stations, of '8. switching mechanism at each station,'a telephone receiver at each station normally connected in a closed bridge of said conductors, means. by which upon operating said switching mechanisms said-bridges will, opened on'both sides of the receivers, and means by which-uponany of oflice while two selected stations are in telephonic connectionwith each other, and means by which such emer- 

